The relationship between vitamin A and zinc in plasma and liver of cattle

Numerous abnormalities and clinical syndromes have been associated with vitamin A and zinc deficiency in large animals. In addition, zinc status influences several aspects of vitamin A metabolism including its mobilization from liver to other tissues. The purpose of the present study is to determine the vitamin A and zinc status and their relationship in cattle. Vitamin A and zinc concentrations in blood plasma and liver samples of 114 to 130 male slaughtered cattle (under 18 months old) in Urmia were assessed and their status and correlations were analyzed. In 15.6, 25.4, 5.4 and 3.8% of samples, the concentrations of vitamin A and zinc in plasma and liver were less than minimum recommended concentration, respectively. In 24.8% of samples vitamin A in liver was more than maximum recommended concentration. The mean concentrations (±standard error) of vitamin A and zinc in plasma and vitamin A and zinc in liver were 59.7±4.5 µg/dL, 99.1±4.7 µg/dL, 161.9±6.2 µg/g wet weight and 103.2±4.7 µg/g wet weight, respectively. In cattle with zinc levels lower than minimum reference value, vitamin A in plasma and zinc concentration in liver were significantly (p<0.0005) less than those of cattle with normal plasma zinc levels. In cattle with inadequate zinc status a direct significant correlation (p<0.01, r=0.481) between plasma and liver vitamin A levels was observed. However, in cattle with adequate zinc status, the plasma zinc had a positive significant correlation with plasma vitamin A (p<0.01, r=0.466), liver vitamin A (p<0.01, r=0.411) and liver zinc (p<0.01, r=372). Deficiency of vitamin A and zinc are relatively common in Urmia and the deficiency probably leads to subclinical and clinical abnormalities. Furthermore, zinc had significant effects on plasma and liver vitamin A status.